Looking at the pattern I was a little dubious, as 80 STS felted was around the width of the felted oven mitts I've made, and would not be nearly large enough to fit on my head. Rather than change the stitches of the pattern, I decided to knit with two strands of wool of the Andes yarn without changing the needles size. In my experience, projects shrink more in the length than the width, so I made the hat very long:
The pattern is cute before it was felted, with a horizontal stripe form the garter stitch and almost vertical stripes from stockinette (This effect is still apparent after I felted the hat).
As knitted, the hat would work (pre-felting) if it were folded up with a brim. As you may notice, this hat fits pretty well before I started felting. I do my felting by hand anyway, so I kept a close eye on the progress to ensure that it would still fit my head.